Although segmental tunnel linings are often used for seismic areas, the influence of segment joints on the segmental lining behavior under seismic loading has not been thoroughly considered in the literature. This paper presents the results of a numerical study investigating the effects of the rotational, axial, and radial joint stiffness of the longitudinal joints on the structural force...

Free rotational aerophones such as the bullroarer, which consists of a wooden slat whirled around on the end of a string, and which emits a loud pulsating roar, have been used in many ancient and traditional societies for ceremonial purposes. This article presents an experimental and theoretical investigation of this instrument. The aerodynamics of rotational behavior is elucidated, and relates...

multivariate process capability indices (mpci) show how well a manufacturing process can meet specifica-tion limits when quality characteristics enclose a relative correlation. process capability is an important and commonly used metric for assessing and improving the quality of a production process. when quality charac-teristics of a product are correlated then an attractive comes close to mpc...

The cooling of molecules during the adiabatic expansion of supersonic seeded molecular beams is reviewed and illustrated by the example of NO -molecules. The reduction of the Doppler width by collimation of the beam and the cooling to low rotational temperatures brings a significant simplification of the complex NO -absorption spectrum and allows its assignment. The measured rotational tem...

The use of optical emission spectroscopy and specifically the OH(A-X) rotational distribution is investigated to obtain gas temperatures in plasmas in and in contact with liquids. The rotational distribution of OH(A-X) is often non-Boltzmann and only the rotational lines with the smallest rotational numbers are in equilibrium with the gas temperature. The possible reasons of this non-equilibriu...

To track moving targets undergoing unknown translational and rotational motions, a tracking controller is developed for unmanned aerial vehicles (UAVs). The main challenges are to control both the relative position orientation between target UAV within desired values, guarantee that generated input feasible (i.e., below its motion capability). Moreover, controlled ensure always remains field of...

Abstract Graphene has the capability of dynamically tuning its conductivity through gate voltage. Based on this fact, an electrically switchable wideband metamaterial absorber at low frequencies is presented and investigated in paper. Our calculated results show that absorption over 90% from 400 to 1,000 MHz with Fermi level graphene being 0 eV band can be switched by adjusting without changing...

Nowadays, piezoelectric materials have wide applications in various industries. Therefore, investigation of these materials and their applications has a special importance. In this paper first, the natural frequencies of a traveling-wave piezoelectric motor are achieved, using finite elements simulations. Then, applying an alternative electrical voltage to the piezoelectric ring, a traveling wa...

The basic aim of present study is to examine the effect of main friction stir welding (FSW) parameters on the quality of AA 6063 plate welds. Welding of AA6063 was carried out by a vertical milling machine, using different tools with a stationary shoulder and during the welding no external heating system was used. Different welding parameters studied were the tool rotational speed which varied ...

In this paper, vibration analysis of multiple-stepped Bernoulli-Euler and Timoshenko beams carrying point masses is presented analytically for various boundary conditions. Each attached element is considered to have both translational and rotational inertias. The method of solution is “transfer matrix method” which is based on the changes in the vibration modes at the vicinity of any discontinu...